package com.example.base.view;

import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;

import android.view.View;
import android.view.ViewGroup;


import java.util.HashMap;

import java.util.Map;

public class SysViewLayout extends ViewGroup {

  public SysViewLayout(Context context) {
    super(context);
  }

  public SysViewLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  public SysViewLayout(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    //   super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    //遍历去调用所有子元素的measure方法（child.getMeasuredHeight()才能获取到值，否则为0）
    measureChildren(widthMeasureSpec, heightMeasureSpec);

    int measuredWidth = 0, measuredHeight = 0;

    int widthSize = MeasureSpec.getSize(widthMeasureSpec);
    int widtMode = MeasureSpec.getMode(widthMeasureSpec);
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    int heightSize = MeasureSpec.getSize(heightMeasureSpec);
    //由于计算子view所占宽度，这里传值需要自身减去PaddingRight宽度，PaddingLeft会在接下来计算子元素位置时加上
    Map<String, Integer> compute = compute(widthSize - getPaddingRight());

    //EXACTLY模式：对应于给定大小或者match_parent情况
    if (widtMode == MeasureSpec.EXACTLY) {
      measuredWidth = widthSize;
      //AT_MOS模式：对应wrap-content（需要手动计算大小，否则相当于match_parent）
    } else if (widtMode == MeasureSpec.AT_MOST) {
      measuredWidth = compute.get("allChildWidth");
    }

//        if (heightMode == MeasureSpec.EXACTLY) {
//            measuredHeight = heightSize;
//        } else if (heightMode == MeasureSpec.AT_MOST) {
    measuredHeight = compute.get("allChildHeight");
//        }
    //设置flow的宽高
    setMeasuredDimension(measuredWidth, measuredHeight);
  }

  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    for (int i = 0; i < getChildCount(); i++) {
      View child = getChildAt(i);
      Rect rect = (Rect) getChildAt(i).getTag();
      child.layout(rect.left, rect.top, rect.right, rect.bottom);
    }

  }

  /**
   * 测量过程
   *
   * @param flowWidth 该view的宽度
   * @return 返回子元素总所占宽度和高度（用于计算Flowlayout的AT_MOST模式设置宽高）
   */
  private Map<String, Integer> compute(int flowWidth) {
    //是否是单行
    boolean aRow = true;
    MarginLayoutParams marginParams;//子元素margin
    int rowsWidth = getPaddingLeft();//当前行已占宽度(注意需要加上paddingLeft)
    int columnHeight = getPaddingTop();//当前行顶部已占高度(注意需要加上paddingTop)
    int rowsMaxHeight = 0;//当前行所有子元素的最大高度（用于换行累加高度）

    for (int i = 0; i < getChildCount(); i++) {

      View child = getChildAt(i);
      //获取元素测量宽度和高度
      int measuredWidth = child.getMeasuredWidth();
      int measuredHeight = child.getMeasuredHeight();
      //获取元素的margin
      marginParams = (MarginLayoutParams) child.getLayoutParams();
      //子元素所占宽度 = MarginLeft+ child.getMeasuredWidth+MarginRight  注意此时不能child.getWidth,因为界面没有绘制完成，此时wdith为0
      int childWidth = marginParams.leftMargin + marginParams.rightMargin + measuredWidth;
      int childHeight = marginParams.topMargin + marginParams.bottomMargin + measuredHeight;
      //判断是否换行： 该行已占大小+该元素大小>父容器宽度  则换行

      rowsMaxHeight = Math.max(rowsMaxHeight, childHeight);
      //换行
      if (rowsWidth + childWidth > flowWidth) {
        //重置行宽度
        rowsWidth = getPaddingLeft() + getPaddingRight();
        //累加上该行子元素最大高度
        columnHeight += rowsMaxHeight;
        //重置该行最大高度
        rowsMaxHeight = childHeight;
        aRow = false;
      }
      //累加上该行子元素宽度
      rowsWidth += childWidth;
      //判断时占的宽段时加上margin计算，设置顶点位置时不包括margin位置，不然margin会不起作用，这是给View设置tag,在onlayout给子元素设置位置再遍历取出
      child.setTag(new Rect(rowsWidth - childWidth + marginParams.leftMargin, columnHeight + marginParams.topMargin, rowsWidth - marginParams.rightMargin, columnHeight + childHeight - marginParams.bottomMargin));
    }

    //返回子元素总所占宽度和高度（用于计算Flowlayout的AT_MOST模式设置宽高）
    Map<String, Integer> flowMap = new HashMap<>();
    //单行
    if (aRow) {
      flowMap.put("allChildWidth", rowsWidth);
    } else {
      //多行
      flowMap.put("allChildWidth", flowWidth);
    }
    //FlowLayout测量高度 = 当前行顶部已占高度 +当前行内子元素最大高度+FlowLayout的PaddingBottom
    flowMap.put("allChildHeight", columnHeight + rowsMaxHeight + getPaddingBottom());
    return flowMap;
  }
}